Preparation of a molybdenum imide additive composition and lubricating oil compositions containing same

ABSTRACT

The invention is directed to oil soluble additive compositions, lubricating oil compositions, and additive concentrates. The oil soluble additive composition comprises a salt or complex of (i) a molybdenum component which comprises a molybdenum oxide, sulfide, or oxysulfide of the general formula MoO x S y  wherein x≧0, y≧0, and 12≧(x+y)≧2; and (ii) an imide wherein said imide comprises the reaction product of at least one dicarboxylic acid component having from about 8 to about 22 carbon atoms, and at least one nitrogen compound selected from ammonia and a polyamine.

FIELD OF THE INVENTION

This invention relates to new lubricating oil additives and lubricatingoil compositions. More specifically, it relates to new lubricating oilcompositions containing a friction reducing component comprising thesalt or complex of a molybdenum oxide, sulfide, or oxysulfide and animide.

BACKGROUND OF THE INVENTION

Molybdenum disulfide has long been known as a desirable additive for usein lubricating oil compositions. Molybdenum disulfide is ordinarilyfinely ground and then dispersed in the lubricating oil composition toimpart friction modifying and antiwear properties. However, one of themajor detriments to using finely ground molybdenum disulfide is its lackof solubility.

As an alternative to using finely ground molybdenum disulfide as afriction modifier, a number of other approaches involving various saltsof molybdenum compounds have been employed. Molybdenum dithiocarbamates(MoDTC) and molybdenum dithiophosphates (MoDTP) are well known in theart to impart friction modifying properties. Representative compositionsof MoDTC are described in Larson et al., U.S. Pat. No. 3,419,589, whichteaches molybdenum (VI) dioxide dialkyldithiocarbamates; Farmer et al.,U.S. Pat. No. 3,509,051, which teaches sulfurized oxymolybdenumdithiocarbamates; and Sakurai et al., U.S. Pat. No. 4,098,705, whichteaches sulfur containing molybdenum dihydrocarbyl dithiocarbamatecompositions.

Representative compounds of MoDTP are the compositions described inRowan et al., U.S. Pat. No. 3,494,866, such as oxymolybdenumdiisopropylphosphorodithioate.

Another method of incorporating molybdenum compounds in oil is toprepare a colloidal complex of molybdenum disulfide or oxysulfidesdispersed using known dispersants. Known dispersants include basicnitrogen containing compounds including succinimides, carboxylic acidamides, phosphonoamides, thiophosphonoamides, Mannich bases, andhydrocarbonpolyamines.

King et al., U.S. Pat. No. 4,263,152; King et al., U.S. Pat. No.4,261,843; and King et al., U.S. Pat. No. 4,259,195 teach molybdenumcompounds used as anti-oxidant and anti-wear additives comprising anacidic molybdenum compound and a basic nitrogen compound which acts as adispersant.

DeVries et al., U.S. Pat. No. 4,259,194 discloses a sulfur containingadditive comprising the reaction product of ammonium tetrathiomolybdateand a basic nitrogen compound for use as an anti-oxidant, anti-wearagent, and friction modifier.

Nemo, U.S. Pat. No. 4,705,643 teaches the preparation of carboxylic acidamides as detergent additives in lubricating oils.

Udding et al., U.S. Pat. No. 5,468,891 describes antifriction additivesfor lubricating oils comprising a molybdenum-containing complex preparedby reacting an alkaline earth metal salt of a carboxylic acid, an amineand a source of cationic molybdenum, wherein the ratio of the number ofequivalents of acid groups to the number of moles of molybdenum (eq:mol)is in the range from 1:10 to 10:1, and the ratio of the number ofequivalents of acid groups to the number of moles of amine (eq:mol) isin the range from 20:1 to 1:10.

Ruhe, Jr. et al., U.S. Pat. No. 6,962,896 describes antioxidantadditives for lubricating oils comprising low color molybdenumcompounds.

Gatto et al., U.S. Pat. No. 6,174,842 discloses a lubricating oilcomposition comprising a lubricating oil, an oil-soluble molybdenumcompound substantially free of reactive sulfur, an oil-solublediarylamine and a calcium phenate as an anti-wear and anti-oxidantadditive.

SUMMARY OF THE INVENTION

In one embodiment, the invention is directed to an oil soluble additivecomposition comprising a salt or complex of (i) a molybdenum componentwhich comprises a molybdenum oxide, sulfide, or oxysulfide of thegeneral formula MoO_(x)S_(y) wherein x≧0, y≧0, and 12≧(x+y)≧2; and (ii)an imide wherein said imide comprises the reaction product of at leastone dicarboxylic acid component having from about 8 to about 22 carbonatoms, and at least one nitrogen compound selected from ammonia and apolyamine.

In one embodiment, the invention is directed to a lubricating oilcomposition comprising an oil of lubricating viscosity and an oilsoluble additive composition comprising a salt or complex of: (i) amolybdenum component which comprises a molybdenum oxide, sulfide, oroxysulfide of the general formula MoO_(x)S_(y) wherein x≧0, y≧0, and12≧(x+y)≧2; and (ii) an imide wherein said imide comprises the reactionproduct of at least one dicarboxylic acid component, having from about 8to about 22 carbon atoms, and at least one nitrogen compound selectedfrom ammonia and a polyamine.

In one embodiment, the invention is directed to a process for preparingan oil soluble additive composition which comprises reacting (i) amolybdenum component which is, or is capable of forming, a molybdenumoxide, sulfide, or oxysulfide of the general formula MoO_(x)S_(y)wherein x≧0, y≧0, and 12≧(x+y)≧2; (ii) an imide which comprises thereaction product of a at least one dicarboxylic acid component havingfrom about 8 to about 22 carbon atoms, and at least one nitrogencompound selected from ammonia and a polyamine component.

DETAILED DESCRIPTION OF THE INVENTION

While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof and are herein describedin detail. It should be understood, however, that the description hereinof specific embodiments is not intended to limit the invention to theparticular forms disclosed, but on the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention as defined by the appended claims.

DEFINITIONS

The following terms will be used throughout the specification and willhave the following meanings unless otherwise indicated.

The term “polyamines” refers to organic compounds containing more thanone basic nitrogen. The organic portion of the compound may containaliphatic, cyclic, or aromatic carbon atoms.

The term “polyalkyleneamines” or “polyalkylenepolyamines” refers tocompounds represented by the general formula

H₂N(—R—NH)_(n)—H

wherein R is an alkylene group of preferably 2-3 carbon atoms and n isan integer of from about 1 to 11.

The term “imide” or “polyimide” typically refers to the reaction productof a dicarboxylic acid, dicarboxylate, anhydride of a dicarboxylic acid,or ester of a dicarboxylic acid and primary amines or ammonia.Typically, imides are compounds that have two carbonyl groups bound tonitrogen and contain five- or six-membered rings. Examples includesuccinimide, phthalimide, and the like.

The terms “molybdenum oxide,” “molybdenum sulfide,” and “molybdenumoxysulfide” refer to compounds of the general formula MoO_(x)S_(y)wherein x≧0, y≧0, and 12≧(x+y)≧2.

The term “dicarboxylic acid component” refers to dicarboxylic acids,dicarboxylates, dicarboxylic anhydrides, and the esters of dicarboxylicacids. Preferred species of dicarboxylic acid components aredicarboxylic acids and dicarboxylic acid anhydrides.

It is believed that the precise molecular formula of the oil solubleadditive composition of the invention comprises the salt or complex of(1) a molybdenum component comprising a molybdenum oxide, sulfide, oroxysulfide and (2) a low molecular weight succinimide, prepared from ahydrocarbyl succinic anhydride and wherein the hydrocarbyl groupcontains from about 8 to about 22 carbon atoms. Although the preciseformulas are not known with certainty, they are believed to be compoundsin which molybdenum, whose valences are satisfied with atoms of oxygenand sulfur, is either complexed by or is the salt of one or more basicnitrogens of the imide used in the preparation of these additives.

Molybdenum Component

The molybdenum component used to prepare the oil soluble additivecomposition of the present invention is a molybdenum containing compoundwhich is a molybdenum oxide, sulfide, or oxysulfide having the generalformula of MoO_(x)S_(y) wherein x≧0, y≧ and 12≧(x+y)≧2. The molybdenumcomponent can include molybdenum in any oxidation state. The molybdenumcomponent useful in the preparation of the oil-soluble additivecomposition of the invention may be derived from molybdenum compoundsincluding, but not limited to, molybdenum hexacarbonyl, molybdic acid,ammonium molybdate, sodium molybdate, potassium molybdate, other alkalimetal molybdates, alkaline earth metal molybdates, MoOCl₄, MoO₂Br₂, andMo₂O₃Cl₆. Other molybdenum components include molybdenum trioxide,ammonium tetrathiomolybdate, and molybdenum disulfide. In oneembodiment, the molybdenum components are molybdenum trioxide and thosecomponents derived from molybdic acid and ammonium molybdate. In oneembodiment, the molybdenum component is molybdenum trioxide.

Imide Component

The dicarboxylic acid component used in the preparation of the oilsoluble additive composition of the invention includes aliphatic andaromatic dicarboxylic acids, dicarboxylic acid salts, dicarboxylic acidanhydrides, or dicarboxylic acid esters having from at least 4 to 40carbon atoms, preferably from 4 to 30 carbon atoms, more preferred from4 to 22 carbon atoms, and even more preferred from 8 to 22 carbon atoms.Examples of dicarboxylic acids include the following: succinic acid,maleic acid, fumaric acid, phthalic acid, glutaconic acid, traumaticacid, muconic acid, sebacic acid, azeloic acid, suberic acid, glutaricacid, adipic acid, pimelic acid, and the like. Alkylated anhydride of acarboxylic acid can also be used, for example, dodecenyl succinicanhydride, hexadecenyl succinic anhydride, and octadecenylsuccnicanhydride, and the like. Mixtures of dicarboxylic acids, dicarboxylicacid salts, dicarboxylic anhydrides, and dicarboxylic acid esters can beused in the preparation of the invention. Preferably, the dicarboxylicacid component is an aliphatic dicarboxylic acid. Particularly preferredanhydrides of dicarboxylic acid components are hexadecenyl succinicanhydride and octadecenyl succinic anhydride.

In one embodiment, dicarboxylic anhydrides are used to prepare thelubricating oil additive composition of the present invention. In oneembodiment, succinimides and polysuccinimides, which are derived fromdicarboxylic anhydrides, may be used to prepare the lubricating oiladditive composition described herein. Preparation of the succinimidesand polysuccinimides is disclosed in numerous references and are wellknown in the art. Certain fundamental types of succinimides and therelated materials encompassed by the term of art “succinimide” aretaught in U.S. Pat. Nos. 3,219,666; 3,172,892; and 3,272,746, thedisclosures of which are hereby incorporated by reference. The term“succinimide” is understood in the art to include many of the amide,imide, and amidine species which may also be formed. The predominantproduct, however, is a succinimide and this term has been generallyaccepted as meaning the product of a reaction of an alkenyl substitutedsuccinic acid or anhydride with a nitrogen-containing compound.Preferred succinimides, because of their commercial availability, arethose succinimides prepared from a hydrocarbyl succinic anhydride,wherein the hydrocarbyl group contains from about 8 to about 22 carbonatoms, and an ethylene amine, said ethylene amines being especiallycharacterized by ethylene diamine, diethylene triamine, triethylenetetramine, tetraethylene pentamine, and higher molecular weightpolyethylene amines. Particularly preferred are those succinimidesprepared from hydrocarbyl succinic anhydride having 8 to 22 carbon atomsand a polyamine component having from about 2 and 10 nitrogens.Preferably, the hydrocarbyl group contains from about 12 to 18 carbonatoms. More preferably, the hydrocarbyl group contains from about 16 to18 carbon atoms.

In one embodiment, the nitrogen compound may be ammonia or a polyaminecomponent. The polyamine component used in the preparation of the oilsoluble additive composition of the present invention includes aromatic,cyclic, and aliphatic (linear and branched) polyamines and mixturesthereof. Examples of aromatic polyamines include, but are not limitedto, phenylenediamine, 2,2′-diaminodiphenylmethane, 2,4- and2,6-diaminotoluene, 2,6-diamino-p-xylene, multi-nuclear and condensedaromatic polyamines such as naphthylene-1,4-diamine, benzidine,2,2′-dichloro-4,4′-diphenyl diamine and 4,4′-diaminoazobenzene. Inanother embodiment the polyamine component comprises polyamines of fromabout 5 to 32 ring members and having from about 2 to 8 amine nitrogenatoms. Such polyamine compounds include such compounds as piperazine,2-methylpiperazine, N-(2-aminoethyl)piperazine,N-(2-hydroxyethyl)piperazine, 1,2-bis-(N-piperazinyl)ethane,3-aminopyrrolidine, N-(2-aminoethyl)pyrrolidine, and aza crown compoundssuch as triazacyclononane, tetraazacyclododecane, and the like.

In a preferred embodiment, the polyamine component used in thepreparation of this invention are polyalkylenepolyamines and can berepresented by the general formula

H₂N(—R—NH)_(n)—H

wherein R is an alkylene group of preferably 2-3 carbon atoms and n isan integer of from 1 to 11.

Specific examples of polyalkylenepolyamines include, but are not limitedto, diethylenetriamine, triethylenetetramine, tetraethylenepentamine,pentaethylenehexamine, hexaethyleneheptamine, heptaethyleneoctamine,octaethylenenonamine, nonaethylenedecamine, decaethyleneundecamine,undecaethylenedodecamine, dipropylenetriamine, tripropylenetetramine,tetrapropylenepentamine, pentapropylenehexamine, hexapropyleneheptamine,heptapropyleneoctamine, octapropylenenonamine, nonapropylenedecamine,decapropyleneundecamine, undecapropylenedodecamine,di(trimethylene)triamine, tri(trimethylene)tetramine,tetra(trimethylene)pentamine, penta(triethylene)hexamine,hexa(trimethylene)heptamine, hepta(trimethylene)octamine,octa(trimethylene)nonamine, nona(trimethylene)decamine,deca(trimethylene)undecamine and undeca(trimethylene)dodecamine.

Succinic acid or anhydride component and an amine component are reactedto form the imide, the charge mole ratio of the succinic acid oranhydride component to amine component is about 6:1 to 1:1. Preferablythe charge mole ratio of the succinic acid or anhydride component toamine component is about 4:1 to 1:1. More preferred, the charge moleratio of the succinic acid or anhydride component to amine component isabout 2:1 to 1:1. In another embodiment, the charge mole ratio of thesuccinic acid or anhydride component to amine component is about 1.5:1to 1:1. In a further embodiment, the charge mole ratio is from about1.7:1 to about 1.3:1.

Promoter

In one embodiment of the present invention, at least one polar promoteris added during the reaction process. The at least one promoter maycomprise a protic polar solvent. In one embodiment, the protic polarsolvent comprises water, methanol and the like.

The protic polar solvent facilitates the interaction between themolybdenum component and the basic nitrogen of the polyamine or imidecomponent. A wide variety of such promoters may be used. Typicalpromoters are alcohols, 1,3-propanediol, 1,4-butanediol, diethyleneglycol, butyl cellosolve, propylene glycol, 1,4-butyleneglycol, methylcarbitol, ethanolamine, diethanolamine, N-methyl-diethanol-amine,dimethyl formamide, N-methyl acetamide, dimethyl acetamide, ammoniumhydroxides, tetra-alkyl ammonium hydroxides, alkali metal hydroxides,methanol, ethylene glycol, dimethyl sulfoxide, hexamethyl phosphoramide,tetrahydrofuran, acetic acid, inorganic acids, and water. Preferred arewater and ethylene glycol. Particularly preferred is water.

While ordinarily the protic polar solvent is separately added to thereaction mixture, it may also be present, particularly in the case ofwater, as a component of non-anhydrous starting materials or as watersof hydration in the molybdenum component, such as (NH₄)₆Mo₇O₂₄.4H₂O.Water may also be added as ammonium hydroxide.

Sulfur Source

In one embodiment, a source of sulfur is added to the reaction processto prepare the additive composition. Representative sulfur sources forpreparing the oil soluble additive compositions of this inventioninclude, but are not limited to sulfur, hydrogen sulfide, sulfurmonochloride, sulfur dichloride, phosphorus pentasulfide, R₂S_(x) whereR is hydrocarbyl, preferably C₁-C₄₀ alkyl, and x is at least 2,inorganic sulfides and polysulfides such as (NH₄)₂S_(x), where x is atleast 1, thioacetamide, thiourea, and mercaptans of the formula RSHwhere R is as defined above. Also useful as sulfurizing agents aretraditional sulfur-containing antioxidants such as wax sulfides andpolysulfides, sulfurized olefins, sulfurized carboxylic acid esters andsulfurized ester-olefins, and sulfurized alkylphenols and the metalsalts thereof.

Preferred sulfur sources are sulfur, hydrogen sulfide, phosphoruspentasulfide, R₂S_(x) where R is hydrocarbyl, preferably C₁-C₁₀ alkyl,and x is at least 3, mercaptans wherein R is C₁-C₁₀ alkyl, inorganicsulfides and polysulfides, thioacetamide, and thiourea. Most preferredsulfur sources are sulfur, hydrogen sulfide, phosphorus pentasulfide,and inorganic sulfides and polysulfides.

Method for Making the Oil Soluble Additive Composition

In one embodiment, the preparation of this invention may be carried outby reacting the molybdenum component with the imide component to form asalt or complex of a molybdenum oxide, sulfide or oxysulfide and animide followed by sulfurization with a sulfur component to form the saltor complex of a molybdenum oxide, sulfide or oxysulfide and an imide.

A diluent may be used to enable the reaction mixture to be efficientlystirred. Typical diluents are lubricating oil and liquid compoundscontaining only carbon and hydrogen. If the mixture is sufficientlyfluid to permit satisfactory mixing, no diluent is necessary. A diluentwhich does not react with the molybdenum component is desirable.

A general method for preparing the oil soluble additive compositions ofthis invention comprises reacting (1) a molybdenum component and (2) animide of a succinic acid or anhydride and an amine in which the succinicacid or anhydride and amine have a charge mole ratio (CMR) of betweenabout 2:1 to 1:1, (3) a protic polar solvent and, optionally, (4) adiluent, to form a salt or complex. The diluent is used, if necessary,to provide a suitable viscosity to facilitate mixing and handling.Typical diluents are lubricating oil and liquid compounds containingonly carbon and hydrogen. Optionally, ammonium hydroxide may also beadded to the reaction mixture to provide a solution of ammoniummolybdate. The molybdenum component, imide, protic polar solvent anddiluent, if used, are charged to a reactor and heated at a temperatureless than or equal to about 200° C., and greater than about 120° C. Thetemperature is maintained at a temperature less than or equal to about200° C., and greater than about 120° C., until the molybdenum componentis sufficiently reacted. The reaction time for this step is typically inthe range of from about 1 to about 30 hours and preferably from about 1to about 10 hours.

Typically excess water and any volatile diluents are removed from thereaction mixture. Removal methods include, but are not limited to,vacuum distillation or nitrogen stripping while maintaining thetemperature of the reactor at a temperature less than or equal to about200° C., and greater than about 120° C. The removal of water andvolatile diluents is ordinarily carried out under reduced pressure. Thepressure may be reduced incrementally to avoid problems with foaming.After the desired pressure is reached, the stripping step is typicallycarried out for a period of about 0.5 to about 5 hours and preferablyfrom about 0.5 to about 2 hours.

The reaction mixture may be further reacted with a sulfur component asdefined above, at a suitable pressure and temperature not to exceed 200°C. The sulfurization step is typically carried out for a period of fromabout 0.5 to about 5 hours and preferably from about 0.5 to about 2hours. In some cases, removal of the polar promoter from the reactionmixture may be desirable prior to completion of reaction with the sulfurcomponent.

The sulfur component is usually charged to the reaction mixture in sucha ratio to provide up to 12 atoms of sulfur per atom of molybdenum. Inone embodiment, the oil soluble composition of the invention will have amole ratio of molybdenum to sulfur of 1:0 to 1:8. In another embodimentthe ratio of molybdenum to sulfur is from about 1:0 to 1:4. In a furtherembodiment, the ratio of molybdenum to sulfur is from about 1:1 to 1:4.

In the reaction mixture the ratio of molybdenum atoms to basic nitrogenatoms provided by the imide can range from about 0.01 to 4.0 atoms ofmolybdenum per basic nitrogen atom. Usually the reaction mixture ischarged from 0.01 to 2.00 atoms of molybdenum per basic nitrogen atomprovided by the imide. Preferably from 0.4 to 1.0, and most preferablyfrom 0.4 to 0.7, atoms of molybdenum per atom of basic nitrogen is addedto the reaction mixture.

The polar promoter, which is preferably water, is ordinarily present inthe ratio of 0.1 to 50 moles of water per mol of molybdenum. Preferablyfrom 0.5 to 25 and most preferably 1.0 to 15 moles of the promoter ispresent per mole of molybdenum.

The charge mole ratio of the succinic acid or anhydride component toamine is critical and can range from about 6:1 to 1:1. In one embodimentthe charge mole ratio is from about 4:1 to 1:1. In one embodiment thecharge mole ratio is from about 2:1 to 1:1. In another embodiment thecharge mole ratio is from about 1.5:1 to 1:1. In a further embodimentthe charge mole ratio is from about 1.7:1 to 1.3:1. The amide formedfrom the reaction of the succinic acid or anhydride component and theamine may occur prior to, during, or after the introduction of themolybdenum component to the reaction mixture.

Specifically, the preparation of the additive composition may beprepared by combining the molybdenum component and the imide component.Furthermore, at least one source of polar promoter is added to thereaction mixture. In one embodiment, at least one source of polarpromoter is added along with the molybdenum, after the imide componenthas been prepared, thereby producing a first reaction product. The imidecomponent can be formed prior to reaction with the molybdenum componentor in situ from a succinic acid or anhydride component and an aminecomponent. The first reaction product—the product of the imide and themolybdenum reaction—is heated, in a first heating step, to at least 80°C. The first reaction product of the molybdenum component and the imidecomponent is sulfurized by reacting with a sulfur component and heating,in a second heating step to drive off any excess polar promoter, themixture at a temperature of greater than 120° C., thereby producing asecond reaction product, which is a salt or complex of a molybdenumoxide, sulfide, or oxysulfide and an imide. In one embodiment thetemperature of the second heating step is at least 140° C.

In one embodiment, the additive composition of the present invention isprepared by mixing and stirring an imide component, base oil and a polarpromoter, such as 2-ethylhexanol, in a first heating step, at atemperature of at least 70° C., thereby producing a reaction mixture. Amolybdenum component and at least one source of water are added to thereaction mixture and heated, in a second heating step, to at least 85°C., thereby producing a first reaction product. The first reactionproduct is further heated, in a third heating step, to at least 170° C.to remove 2-ethylhexanol. The temperature is decreased, in a fourthheating step, to no more than 100° C. A source of sulfur is added to thefirst reaction product, thereby producing a second reaction productwhich is then heated, in a fifth heating step, to at least 120° C. Inone embodiment the temperature of the fifth heating step is at least140° C.

Additive Concentrates

In many instances, it may be advantageous to form concentrates of theoil soluble additive composition of the present invention within acarrier liquid. These additive concentrates provide a convenient methodof handling, transporting, and ultimately blending into lubricant baseoils to provide a finished lubricant. Generally, the oil solubleadditive concentrates of the invention are not useable or suitable asfinished lubricants on their own. Rather, the oil soluble additiveconcentrates are blended with lubricant base oil stocks to provide afinished lubricant. It is desired that the carrier liquid readilysolubilizes the oil soluble additive of the invention and provides anoil additive concentrate that is readily soluble in the lubricant baseoil stocks. In addition, it is desired that the carrier liquid notintroduce any undesirable characteristics, including, for example, highvolatility, high viscosity, and impurities such as heteroatoms, to thelubricant base oil stocks and thus, ultimately to the finishedlubricant. The present invention therefore further provides an oilsoluble additive concentrate composition comprising an inert carrierfluid and from 2.0% to 90% by weight, based on the total concentrate, ofan oil soluble additive composition according to the invention. Theinert carrier fluid may be a lubricating oil.

These concentrates usually contain from about 2.0% to about 90% byweight, preferably 10% to 50% by weight of the oil soluble additivecomposition of this invention and may contain, in addition, one or moreother additives known in the art and described below. The remainder ofthe concentrate is the substantially inert carrier liquid.

Lubricating Oil Compositions

In one embodiment of the invention, the oil soluble additive compositionof the present invention can be mixed with a base oil of lubricatingviscosity to form a lubricating oil composition. The lubricating oilcomposition comprises a major amount of a base oil of lubricatingviscosity and a minor amount of the oil soluble additive composition ofthe present invention described above.

The lubricating oil which may be used in this invention includes a widevariety of hydrocarbon oils, such as naphthenic bases, paraffin basesand mixed base oils as well as synthetic oils such as esters and thelike. The lubricating oils which may be used in this invention alsoinclude oils from biomass such as plant and animal derived oils. Thelubricating oils may be used individually or in combination andgenerally have a viscosity which ranges from 7 to 3,300 cSt and usuallyfrom 20 to 2000 cSt at 40° C. Thus, the base oil can be a refinedparaffin type base oil, a refined naphthenic base oil, or a synthetichydrocarbon or non-hydrocarbon oil of lubricating viscosity. The baseoil can also be a mixture of mineral and synthetic oils. Mineral oilsfor use as the base oil in this invention include, for example,paraffinic, naphthenic and other oils that are ordinarily used inlubricating oil compositions. Synthetic oils include, for example, bothhydrocarbon synthetic oils and synthetic esters and mixtures thereofhaving the desired viscosity. Hydrocarbon synthetic oils may include,for example, oils prepared from the polymerization of ethylene, i.e.,polyalphaolefin or PAO, or from hydrocarbon synthesis procedures usingcarbon monoxide and hydrogen gases such as in a Fisher-Tropsch process.Useful synthetic hydrocarbon oils include liquid polymers of alphaolefins having the proper viscosity. Likewise, alkyl benzenes of properviscosity, such as didodecyl benzene, can be used. Useful syntheticesters include the esters of monocarboxylic acids and polycarboxylicacids, as well as mono-hydroxy alkanols and polyols. Typical examplesare didodecyl adipate, pentaerythritol tetracaproate, di-2-ethylhexyladipate, dilaurylsebacate, and the like. Complex esters prepared frommixtures of mono and dicarboxylic acids and mono and dihydroxy alkanolscan also be used. Blends of mineral oils with synthetic oils are alsouseful.

The lubricating oil compositions containing the oil soluble additives ofthis invention can be prepared by admixing, by conventional techniques,the appropriate amount of the oil soluble additives of the inventionwith a lubricating oil. The selection of the particular base oil dependson the contemplated application of the lubricant and the presence ofother additives. Generally, the amount of the oil soluble additivecomposition of the invention in the lubricating oil composition of theinvention will vary from 0.05 to 15% by weight and preferably from 0.2to 1% by weight, based on the total weight of the lubricating oilcomposition. In one embodiment, the molybdenum content of thelubricating oil composition will be between about 50 parts per million(ppm) and 5000 ppm, preferably between about 90 ppm to 1500 ppm. Inanother embodiment the molybdenum content of the lubricating oilcomposition will be between about 500 ppm and 700 ppm.

Additional Additives

If desired, other additives may be included in the lubricating oil andlubricating oil concentrate compositions of this invention. Theseadditives include antioxidants or oxidation inhibitors, dispersants,rust inhibitors, anticorrosion agents and so forth. Also, anti-foamagents, stabilizers, anti-stain agents, tackiness agents, anti-chatteragents, dropping point improvers, anti-squawk agents, extreme pressureagents, odor control agents and the like may be included.

The following additive components are examples of some of the componentsthat can be favorably employed in the lubricating oil compositions ofthe present invention. These examples of additional additives areprovided to illustrate the present invention, but they are not intendedto limit it:

Metal Detergents

Detergents which may be employed in the present invention include alkylor alkenyl aromatic sulfonates, calcium phenate, borated sulfonates,sulfurized or unsulfurized metal salts of multi-hydroxy alkyl or alkenylaromatic compounds, alkyl or alkenyl hydroxy aromatic sulfonates,sulfurized or unsulfurized alkyl or alkenyl naphthenates, metal salts ofalkanoic acids, metal salts of an alkyl or alkenyl multiacid, andchemical and physical mixtures thereof.

Anti-Wear Agents

As their name implies, these agents reduce wear of moving metallicparts. Examples of such agents include, but are not limited to, zincdithiophosphates, carbarmates, esters, and molybdenum complexes.

Rust Inhibitors (Anti-Rust Agents)

Anti-rust agents reduce corrosion on materials normally subject tocorrosion. Examples of anti-rust agents include, but are not limited to,nonionic polyoxyethylene surface active agents such as polyoxyethylenelauryl ether, polyoxyethylene higher alcohol ether, polyoxyethylenenonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethyleneoctyl stearyl ether, polyoxyethylene oleyl ether, polyoxyethylenesorbitol monostearate, polyoxyethylene sorbitol mono-oleate, andpolyethylene glycol mono-oleate. Other compounds useful as anti-rustagents include, but are not limited to, stearic acid and other fattyacids, dicarboxylic acids, metal soaps, fatty acid amine salts, metalsalts of heavy sulfonic acid, partial carboxylic acid ester ofpolyhydric alcohol, and phosphoric ester.

Demulsifiers

Demulsifiers are used to aid the separation of an emulsion. Examples ofdemulsifiers include, but are not limited to, block copolymers ofpolyethylene glycol and polypropylene glycol, polyethoxylatedalkylphenols, polyesteramides, ethoxylated alkylphenol-formaldehyderesins, polyvinylalcohol derivatives and cationic or anionicpolyelectrolytes. Mixtures of different types of polymers may also beused.

Friction Modifiers

Additional friction modifiers may be added to the lubricating oil of thepresent invention. Examples of friction modifiers include, but are notlimited to, fatty alcohols, fatty acids, amines, ethoxylated amines,borated esters, other esters, phosphates, phosphites and phosphonates.

Multifunctional Additives

Additives with multiple properties such as anti-oxidant and anti-wearproperties may also be added to the lubricating oil of the presentinvention. Examples of multi-functional additives include, but are notlimited to, sulfurized oxymolybdenum dithiocarbamate, sulfurizedoxymolybdenum organo phosphorodithioate, oxymolybdenum monoglyceride,oxymolybdenum diethylate amide, amine-molybdenum complexes, andsulfur-containing molybdenum complexes.

Viscosity Index Improvers

Viscosity index improvers, also known as viscosity modifiers, comprise aclass of additives that improve the viscosity-temperaturecharacteristics of the lubricating oil, making the oil's viscosity morestable as its temperature changes. Viscosity index improvers may beadded to the lubricating oil composition of the present invention.Examples of viscosity index improvers include, but are not limited to,polymethacrylate type polymers, ethylene-propylene copolymers,styrene-isoprene copolymers, alkaline earth metal salts ofphosphosulfurized polyisobutylene, hydrated styrene-isoprene copolymers,polyisobutylene, and dispersant type viscosity index improvers.

Pour Point Depressants

Pour point depressants are polymers that are designed to control waxcrystal formation in lubricating oils resulting in lower pour point andimproved low temperature flow performance. Examples of pour pointdepressants include, but are not limited to, polymethyl methacrylate,ethylene vinyl acetate copolymers, polyethylene polymers, and alkylatedpolystyrenes.

Foam Inhibitors

Foam inhibitors are used to reduce the foaming tendencies of thelubricating oil. Examples of foam inhibitors include, but are notlimited to, alkyl methacrylate polymers, alkylacrylate copolymers, andpolymeric organosiloxanes such as dimethylsiloxane polymers.

Metal Deactivators

Metal deactivators create a film on metal surfaces to prevent the metalfrom causing the oil to be oxidized. Examples of metal deactivatorsinclude, but are not limited to, disalicylidene propylenediamine,triazole derivatives, thiadiazole derivatives, bis-imidazole ethers, andmercaptobenzimidazoles.

Dispersants

Dispersants diffuse sludge, carbon, soot, oxidation products, and otherdeposit precursors to prevent them from coagulating resulting in reduceddeposit formation, less oil oxidation, and less viscosity increase.Examples of dispersants include, but are not limited to, alkenylsuccinimides, alkenyl succinimides modified with other organiccompounds, alkenyl succinimides modified by post-treatment with ethylenecarbonate or boric acid, alkali metal or mixed alkali metal, alkalineearth metal borates, dispersions of hydrated alkali metal borates,dispersions of alkaline-earth metal borates, polyamide ashlessdispersants and the like or mixtures of such dispersants.

Anti-Oxidants

Anti-oxidants reduce the tendency of mineral oils to deteriorate byinhibiting the formation of oxidation products such as sludge andvarnish-like deposits on the metal surfaces. Examples of anti-oxidantsuseful in the present invention include, but are not limited to, phenoltype (phenolic) oxidation inhibitors, such as4,4′-methylene-bis(2,6-di-tert-butylphenol),4,4′-bis(2,6-di-tert-butylphenol),4,4′-bis(2-methyl-6-tert-butylphenol),2,2′-methylene-bis(4-methyl-6-tert-butylphenol),4,4′-butylidene-bis(3-methyl-6-tert-butylphenol),4,4′-isopropylidene-bis(2,6-di-tert-butylphenol),2,2′-methylene-bis(4-methyl-6-nonylphenol),2,2′-isobutylidene-bis(4,6-dimethylphenol),2,2′-5-methylene-bis(4-methyl-6-cyclohexylphenol),2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol,2,4-dimethyl-6-tert-butyl-phenol, 2,6-di-tert-1-dimethylamino-p-cresol,2,6-di-tert-4-(N,N′-dimethylaminomethylphenol),4,4′-thiobis(2-methyl-6-tert-butylphenol),2,2′-thiobis(4-methyl-6-tert-butylphenol),bis(3-methyl-4-hydroxy-5-tert-10-butylbenzyl)-sulfide, andbis(3,5-di-tert-butyl-4-hydroxybenzyl). Diphenylamine-type oxidationinhibitors include, but are not limited to, alkylated diphenylamine,phenyl-alpha-naphthylamine, and alkylated-alpha-naphthylamine. Othertypes of oxidation inhibitors include metal dithiocarbamate (e.g., zincdithiocarbamate), and methylenebis(dibutyldithiocarbamate).

Applications

Lubricating oil compositions containing the oil soluble additivecompositions disclosed herein are effective as either fluid and greasecompositions for modifying the friction properties of the lubricatingoil which may, when used as a crankcase lubricant, lead to improvedmileage for the vehicle being lubricated with a lubricating oil of thisinvention.

The lubricating oil compositions of this invention may be used in marinecylinder lubricants as in crosshead diesel engines, crankcase lubricantsas in automobiles and railroads, lubricants for heavy machinery such assteel mills and the like, or as greases for bearings and the like.Whether the lubricant is fluid or solid will ordinarily depend onwhether a thickening agent is present. Typical thickening agents includepolyurea acetates, lithium stearate and the like. The oil solubleadditive composition of the invention may also find utility as ananti-oxidant, anti-wear additive in explosive emulsion formulations.

The following examples are presented to illustrate specific embodimentsof this invention and are not to be construed in any way as limiting thescope of the invention

EXAMPLES Example 1

In a 3-neck 500 mL glass reactor equipped with a temperature controller,mechanical stirrer, and water cooled condenser, 27.1 g of a succinimide,prepared from a hexadecenyl succinic anhydride (HDSA) and triethylenetetramine (TETA) at a molar ratio of TETA to HDSA of 0.67 to 1, wascharged. Additionally, 12.3 g of 100 neutral oil, and 70 mL of xylenewere charged to the glass reactor. The mixture was heated to atemperature of 85° C. where upon, 2.98 g of molybdenum oxide and 3.0 gof water were charged to the reactor. The reactor was then held at areaction temperature of 85° C. for 2.5 hrs. Subsequently 1.33 g ofelemental sulfur was charged to the reactor. The sulfurization reactionwas carried out at 140° C. for 3 hrs, and xylene and water were removedcontinuously with nitrogen sweep.

The product contained 4.50% by weight of molybdenum, 3.06% by weight ofsulfur. and 5.1% by weight of nitrogen.

Example 2

A lubricating oil composition was prepared by adding 1.11% by weight(equivalent to 500 ppm of molybdenum) of the lubricating oil additive ofExample 1 to the lubricating oil formulation in Comparative Example A.

Example 3

To a glass reactor equipped with temperature controller, and watercooled condenser, 8.2 g of succinimide as prepared in Example 1, 22.8 gof 2-ethylhexanol, and 3.7 g of 100 neutral oil were charged. Themixture was heated to a temperature of 85° C. where upon 0.90 g ofmolybdenum oxide and 1.0 g of water were charged to the reactor. Thereactor was then held at a reaction temperature of 85° C. for 2 hrs.Upon completion of the molybdation reaction, water and 2-ethylhexanolwere removed by distillation at 170° C. and a pressure of 50 millimetersof mercury (absolute) or less for approximately 30 minutes. The reactionmixture was cooled to 90° C., where upon 0.40 g of elemental sulfur wascharged to the reactor. The sulfurization reaction was carried out at140° C. for 3 hrs.

The product contained 4.57% by weight of molybdenum, 3.06% by weight ofsulfur, and 5.3% by weight of nitrogen.

Example 4

A lubricating oil composition was formed by adding 1.09% by weight(equivalent to 500 ppm of molybdenum) of the lubricating oil additive ofExample 3 to lubricating oil formulation in Comparative Example A.

Comparative Example A

A baseline lubricating oil formulation was formed containing 4% byweight of an ashless dispersant, 3.01% by weight of alkaline earth metalcarboxylate detergent, 0.62% by weight of a zinc dialkyldithiophosphate,1.2% by weight of an antioxidant, 4.3% by weight of a non-dispersanttype viscosity index improver, 5 ppm of a foam inhibitor in a Group IIbase oil.

Comparative Example B

A lubricating oil composition was prepared by adding 500 ppm ofmolybdenum oxysulfide succinimide complex, derived from a polyisobutenyl(having an average molecular weight of 1000) succinimide, as describedin Ruhe et al, U.S. Pat. No. 6,962,896 to lubricating oil formulation inComparative Example A.

Comparative Example C

A lubricating oil composition was prepared by adding 500 ppm ofmolybdenum oxysulfide succinimide complex, derived from a polyisobutenyl(having an average molecular weight of 1000) succinimide, as describedin King et al, U.S. Pat. No. 4,263,152 to lubricating oil formulation inComparative Example A.

Comparative Example D

A lubricating oil composition was prepared by adding 0.82% by weight(equivalent to 500 ppm of molybdenum) of molybdenum dithiocarbamate(MoDTC, available from AdekaUSA Corporation, Saddle River, N.J.) tolubricating oil formulation in Comparative Example A.

Example 5

To a glass reactor equipped with a temperature controller, and watercooled condenser, 8.0 g of a succinimide, prepared from a octadecenylsuccinic anhydride (ODSA) and tetraethylene pentamine (TEPA) at a molarratio of amine to ODSA of 1.0 to 1.0, 2.0 g of neutral oil, and 25.0 gof toluene were charged The mixture was heated to 85° C. where upon 1.10g of molybdenum oxide and 2.0 g of water were charged to the reactor.The reactor was then held at a reaction temperature of 85° C. for 1.5hrs. Upon completion of the molybdation reaction, 0.49 g of elementalsulfur was charged to the reactor. The sulfurization reaction wascarried out at 105° C. for 3 hrs. The reaction mixture was then filteredthrough filter aid and toluene and water were removed using rotoryevaporator.

The product contained 2.06% by weight of molybdenum and 2.34% by weightof sulfur.

Example 6

A lubricating oil composition was prepared by adding 500 ppm ofmolybdenum of the lubricating oil additive of Example 5 to lubricatingoil formulation in Comparative Example A.

Comparative Example E

A lubricating oil composition was prepared by adding 500 ppm ofmolybdenum dialkyldithiophosphate (MoDTP, available as “Molyvan L” fromR.T. Vanderbilt Company, Norwalk, Conn.) to lubricating oil formulationin Comparative Example A.

The compositions described above were tested for friction performance ina Mini-Traction Machine (MTM) bench test. The MTM is manufactured by PCSInstruments and operates in pin-on-disk configuration in which astainless steel ball (6 mm) is loaded against a rotating disk (32100steel). The condition employs a load of 10 Newtons, a speed of 500 mm/s,temperature of 120° C., and has a run-time of 60 minutes. The resultsare averaged for the last 10 minutes and are summarized in the Table 1.

TABLE 1 Comparison of Coefficients of Friction (COF) for VariousExamples: Coefficient of Mo ppm in Friction (avg. of ExamplesDescription finished oil last 10 mins) 2 C16 500 0.054 succinimide 4 C16500 0.053 succinimide 6 C18 500 0.067 succinimide Comp. A (baseline) 00.128 Comp. B 1000MW PIB 500 0.115 succinimide Comp. C 1000MW PIB 5000.120 succinimide Comp. D MoDTC 500 0.050 Comp. E MoDTP 500 0.047

Examples 2, 4, and 6 in Table 1 show that the coefficients of friction(wherein the lower the COF, the better the friction reducing properties)of the lubricating oil composition of the present invention iscomparable to that of molybdenum dithiocarbamate (Comp. D) andmolybdenum dithiophosphate (Comp. E), both are well know frictionreducers. Examples 2, 4, and 6 also show superior friction reducingproperties as compared to a molybdenum succinimide complex synthesizedfrom a polyisobutenyl succinimide wherein the polyisobutenyl group hasaround 1000 molecular weight equivalent of carbon atoms (Comp. B and C).As evidenced by the data in Table 1, friction reducing properties areimproved when a lower molecular weight hydrocarbyl succinimide (e.g.,about 16 to 18 carbon atoms) is employed.

1. An oil soluble additive composition comprising a salt or complex of(i) a molybdenum component which comprises a molybdenum oxide, sulfide,or oxysulfide of the general formula MoO_(x)S_(y) wherein x≧0, y≧0, and12≧(x+y)≧2; and (ii) an imide wherein said imide comprises the reactionproduct of at least one dicarboxylic acid component having from about 8to about 22 carbon atoms, and at least one nitrogen compound selectedfrom ammonia and a polyamine.
 2. The oil soluble additive composition ofclaim 1, wherein the molybdenum component is a molybdenum sulfide. 3.The oil soluble additive composition of claim 1, wherein the imidecontains at least one basic nitrogen.
 4. The oil soluble additivecomposition of claim 1, wherein the imide is a phthalamide.
 5. The oilsoluble additive composition of claim 1, wherein the imide is ahydrocarbyl succinimide.
 6. The oil soluble additive composition ofclaim 5 wherein the hydrocarbyl succinimide is prepared from ahydrocarbyl succinic anhydride and wherein the hydrocarbyl groupcontains from about 8 to about 22 carbon atoms.
 7. The oil solubleadditive composition of claim 1, wherein the dicarboxylic acid componentis a dicarboxylic acid, dicarboxylic acid salt, dicarboxylic acidanhydride, dicarboxylic acid ester, or mixtures thereof.
 8. The oilsoluble additive composition of claim 1, wherein the dicarboxylic acidcomponent is a hydrocarbyl dicarboxylic acid wherein the hydrocarbylgroup contains from about 8 to about 22 carbon atoms.
 9. The oil solubleadditive composition of claim 1, wherein the charge mole ratio of thedicarboxylic acid component to the nitrogen compound is about 6:1 to1:1.
 10. The oil soluble additive composition of claim 1, wherein thepolyamine is a polyalkylenepolyamine of the general formulaH₂N(—R—NH)_(n)—H and wherein R is an alkylene group of 2-3 carbon atomsand n is an integer of from 1 to
 11. 11. The oil soluble composition ofclaim 1, wherein the polyamine is tetraethylenepentamine (TEPA),diethylenetriamine (DETA), ethylenediamine (EDA), or mixtures thereof.12. The oil soluble additive composition of claim 1, wherein themolybdenum component is sulfurized.
 13. The oil soluble additivecomposition of claim 1, wherein the mole ratio of molybdenum to sulfurin the oil soluble additive composition is about 1:0 to 1:8.
 14. Alubricating oil composition comprising: (1) an oil of lubricatingviscosity and (2) an oil soluble additive composition comprising a saltor complex of: (i) a molybdenum component which comprises a molybdenumoxide, sulfide, or oxysulfide of the general formula MoO_(x)S_(y)wherein x≧0, y≧0, and 12≧(x+y)≧2; and (ii) an imide wherein said imidecomprises the reaction product of at least one dicarboxylic acidcomponent, having from about 8 to about 22 carbon atoms, and at leastone nitrogen compound selected from ammonia and a polyamine.
 15. Thelubricating oil composition of claim 14, wherein the molybdenum contentof the lubricating oil composition is between about 50 ppm and 5000 ppm.16. The lubricating oil composition of claim 14, wherein the oil solubleadditive composition content is between 0.05 to 15% by weight.
 17. Aprocess for preparing an oil soluble additive composition whichcomprises reacting: (i) a molybdenum component which is, or is capableof forming, a molybdenum oxide, sulfide, or oxysulfide of the generalformula MoO_(x)S_(y) wherein x≧0, y≧0, and 12≧(x+y)≧2; (ii) an imidewhich comprises the reaction product of a at least one dicarboxylic acidcomponent having from about 8 to about 22 carbon atoms, and at least onenitrogen compound selected from ammonia and a polyamine component. 18.The process of claim 17, wherein the product obtained from the reactionof step (i) and step (ii) is sulfurized in an amount sufficient toprovide 0.01 to 12 atoms of sulfur per atom of molybdenum.
 19. Theprocess of claim 17, wherein the reaction of the molybdenum componentand the imide is in the presence of a polar promoter.
 20. The process ofclaim 19, wherein the polar promoter is selected from the groupconsisting of 1,3-propanediol, 1,4-butanediol, diethylene glycol, butylcellosolve, propylene glycol, 1,4-butyleneglycol, methyl carbitol,ethanolamine, ammonium hydroxide, alkyl ammonium hydroxide, metalhydroxide, N-methyl-diethanol-amine, dimethyl formamide, N-methylacetamide, dimethyl acetamide, methanol, ethylene glycol, dimethylsulfoxide, hexamethyl phosphoramide, tetrahydrofuran, water, inorganicacid, and mixtures thereof.
 21. The process of claim 20, wherein thepolar promoter is water.
 22. The process of claim 18, wherein thesulfurization is carried out with a sulfur source selected from sulfur,hydrogen sulfide, phosphorus pentasulfide, R₂S_(x) where R ishydrocarbyl, and x is at least 2, inorganic sulfides or inorganicpolysulfides, thioacetamide, thiourea, mercaptans of the formula RSHwhere R is hydrocarbyl, or a sulfur-containing antioxidant.
 23. Theprocess of claim 17, wherein the molybdenum component is selected fromthe group consisting of molybdic acid, ammonium molybdate, sodiummolybdate, potassium molybdate, metal molybdates, MoOC₁₄, MoO₂Br₂,Mo₂O₃C₁₆, molybdenum trioxide, and mixtures thereof.
 24. The process ofclaim 17, wherein the molybdenum component is molybdenum trioxide. 25.The process of claim 17, wherein the dicarboxylic acid componentcomprises at least one hydrocarbyl succinic acid or anhydride.
 26. Theprocess of claim 17, wherein the polyamine component comprises apolyalkylenepolyamine represented by the general formulaH₂N(—R—NH)_(n)—H and wherein R is an alkylene group of 2-3 carbon atomsand n is an integer of from 1 to
 11. 27. The process of claim 17,wherein the polyamine component is tetraethylenepentamine (TEPA),diethylenetriamine (DETA), ethylenediamine (EDA), or mixtures thereof.